I'm not currently running a M&M campaign, so I can't comment on how well any of these villains actual come off in a game session or adventure. However, they certainly sparked my imagination, and fit in well with a Hallowe'en theme. For a product like this, the stat blocks are obviously essential; I also appreciated the "Caper Ideas" (adventure seeds) provided for each villain, though the word "caper" seems a bit weak for some of these menaces.
I particularly like Armageddon, the Horseman, and Pumpkin Jack. Graveside is an interesting character, and a good pregenerated Dracula could be useful. The Bogeyman didn't do much for me. Of course, any product that brings Cthulhu into Mutants & Masterminds is worth having!
Some of the artwork and writing seemed a little amateurish, but overall, I'm glad to have this PDF in my M&M collection.